Capacitive priming sensor for a medical fluid delivery system

ABSTRACT

A capacitive priming sensor for a medical fluid delivery system is disclosed. In an example embodiment, a priming sensor includes a housing including a recessed section configured to accept a portion of a patient tube. The housing includes a first electrode located adjacent to a portion of the patient tube when the portion of the patient tube is inserted into the housing and a second electrode located above the first electrode. The priming sensor also includes a capacitive sensor that measures a capacitance between the first electrode and the second electrode. A processor operates with the capacitive sensor and is configured to use the measured capacitance to determine a transition between a dry tube state and a wet tube state. The processor then causes a pump to stop pumping dialysis fluid through the patient tube for the priming sequence after the wet tube state is determined.

PRIORITY CLAIM

This application claims priority to and the benefit as a continuationapplication of U.S. patent application Ser. No. 16/986,789, filed Aug.6, 2020, which is a non-provisional application of U.S. ProvisionalPatent Application No. 62/884,862, filed Aug. 9, 2019, the entirecontents of which are hereby incorporated by reference and relied upon.

TECHNICAL FIELD

The present disclosure relates generally to medical fluid delivery, andmore particularly to a capacitive priming sensor for an automatedperitoneal dialysis (“APD”) machine.

BACKGROUND

People with damaged or improperly functioning kidneys may undergodialysis treatments to remove waste products from blood. One common typeof dialysis is peritoneal dialysis (“PD”), in which a cleansing fluid,referred to as PD or dialysis fluid, is delivered to a patient'speritoneal cavity of their abdomen via a catheter. The cleansing fluidabsorbs waste products during a dwell period. After the dwell periodends, the cleansing fluid is removed from the patient's peritonealcavity along with the absorbed waste products and excess water (known asultrafiltration), thereby compensating for the patient's improperlyfunctioning kidneys.

An automated peritoneal dialysis (“APD”) machine is used in manyinstances to pump a prescribed volume of a PD or dialysis fluid (e.g., acleansing fluid) into a patient's peritoneal cavity. The APD machine isconfigured to permit the dialysis fluid to remain in the patient duringthe dwell period. After the dwell period, the APD machine drains useddialysis fluid or effluent containing waste products from the patient'speritoneal cavity. APD machines typically prime tubes and/or a tubingset that routes the dialysis fluid to the patient. The priming of thetubes and/or tubing set removes air, thereby preventing the air frombeing transmitted into the patient's peritoneal cavity. Priming mayinvolve pumping the dialysis fluid to an end of a tube, such as apatient line that is later connected to the patient during the PDtreatment, to remove the air within the tube.

APD machines are typically located in a patient's home, a clinic, or ahospital. In many instances, a patient prepares the APD machine fortreatment by performing a priming sequence. To aid in priming the tubes,APD machines may include a sensor that detects when a tube is properlyprimed. Known sensors have used light to detect when the dialysis fluidhas reached the end of a tube, which is indicative of a successfulprime. However, fluctuations in ambient light, tube properties, tubegeometries, and/or fluid type may cause the light sensor to be lessaccurate than desired.

SUMMARY

The example system, apparatus, and method disclosed herein areconfigured to provide an accurate medical fluid treatment priming sensorthat is insensitive to ambient light brightness, tube properties, and/orfluid type. The dialysis priming sensor disclosed herein usescapacitance sensing. The priming sensor may include a housing thatencloses electrodes and/or conductive plates that are connected to oneor more sensors that measure a capacitance between the electrodes and/orconductive plates. The electrodes and/or conductive plates arepositioned within the housing to form one or more capacitors. Theelectrodes and/or conductive plates may be located on opposite sides ofthe housing for detecting a fluid level based on a capacitance changewhen a medical fluid (e.g., dialysis fluid, dialysate, tap water, orother conductive fluids) flows through the inserted tube past theelectrodes and/or conductive plates. Additionally or alternatively, atleast some of the electrodes and/or conductive plates may be placed atdifferent heights with respect to a patient tube placed in the primingsensor. The positioning of the electrodes and/or conductive plates atdifferent heights aids in the detection of the patient tube. Placementof the patient tube in the housing of the priming sensor causes at leastone electrode and/or conductive plate to move relative to otherstationary electrode(s) and/or conductive plate(s) that are placed atdifferent heights, thereby causing a change in capacitance for detectingthe presence of the tube. In some embodiments, the positioning of theelectrodes and/or conductive plates at different heights provides foradditionally or alternatively detecting a fluid level in the patienttube.

A processor (or a control unit having one or more processors and one ormore memories) analyzes the output from the one or more capacitivesensors to determine whether a patient tube is present and insertedwithin the priming sensor housing (e.g., detecting between a no-tubestate and a dry tube state). The processor or the control unit is alsoconfigured to determine when a medical fluid such as dialysis fluidreaches a certain level in the patient tube corresponding to asuccessful prime (e.g., detecting between a dry state and a wet state).After detecting that a tube is present and includes a fluid (e.g., a wettube state), the processor or the control unit is further configured toprovide an indication that priming of a patient line for PD therapy issuccessful, which permits the priming sequence to continue/end and/or aPD treatment to begin. In some instances, the processor or the controlunit may also provide an indication that the dry tube state is notpresent. The processor or the control unit may also be configured toprovide an indication of a failed prime of the patient line if, forexample, the tube itself is not detected or the wet tube state of thetube is not detected within a defined period of time.

In light of the disclosure herein and without limiting the disclosure inany way, in a first aspect of the present disclosure, which may becombined with any other aspect listed herein unless specified otherwise,a peritoneal dialysis apparatus includes a patient tube configured toreceive dialysis fluid from a source of dialysis fluid, at least onepump configured to move dialysis fluid from the source to the patienttube during a priming sequence, and a priming sensor including a housinghaving a recessed section configured to accept a portion of the patienttube. The recessed section of the housing includes a first sideincluding a first conductive plate, and a member including a secondconductive plate. The member is moveably connected to a second side ofthe recessed section and configured for a desired movement uponinsertion of the portion of the patient tube into the housing of thepriming sensor. The recessed section also includes a third side opposingthe first side. The third side includes a third conductive platedisposed across from a top portion of the first conductive plate, and afourth conductive plate disposed across from a bottom portion of thefirst conductive plate. The peritoneal dialysis apparatus also includesa first capacitive sensor positioned and arranged to measure a firstcapacitance between the first conductive plate and the third conductiveplate, a second capacitive sensor positioned and arranged to measure asecond capacitance between the third conductive plate and the fourthconductive plate, and a processor configured to operate with the atleast one pump, the first capacitive sensor, and the second capacitivesensor. The processor is configured to use the measured secondcapacitance to determine a first transition between (i) a no-tube stateand (ii) a dry tube state based on a distance of the second conductiveplate from the third and fourth conductive plates, use the measuredfirst capacitance to determine a second transition between (ii) the drytube state and (iii) a wet tube state based on a presence of fluidwithin the patient tube, cause the at least one pump to pump the fluidthrough the patient tube for the priming sequence after the dry tubestate is determined, and transmit a message indicative that the patienttube is primed after the wet tube state is determined.

In accordance with a second aspect of the present disclosure, which maybe used in combination with any other aspect listed herein unless statedotherwise, the priming sensor includes a third capacitive sensorpositioned and arranged to measure a third capacitance between the firstconductive plate and the fourth conductive plate, and wherein theprocessor is configured to combine values of the first capacitance withvalue of the third capacitance to determine between at least one of (i)the no-tube state and (ii) the dry tube state, or (ii) the dry tubestate and (iii) the wet tube state.

In accordance with a third aspect of the present disclosure, which maybe used in combination with any other aspect listed herein unless statedotherwise, the second conductive plate bends or pivots when the portionof the patient tube is inserted into the housing of the priming sensor,causing the first capacitance to increase.

In accordance with a fourth aspect of the present disclosure, which maybe used in combination with any other aspect listed herein unless statedotherwise, the second conductive plate is at least one of (a) positionedand arranged to electrically float, or (b) formed from a conductiveplastic or a conductively painted plastic.

In accordance with a fifth aspect of the present disclosure, which maybe used in combination with any other aspect listed herein unless statedotherwise, the third conductive plate is at least one of (a) formed witha width that is equal to a width of the fourth conductive plate, or (b)spaced apart from the fourth conductive plate by a distance between 0.5millimeters and 2 centimeters.

In accordance with a sixth aspect of the present disclosure, which maybe used in combination with any other aspect listed herein unless statedotherwise, the first conductive plate, the third conductive plate, andthe fourth conductive plate are at least one of (a) formed as metalclips configured to secure the portion of the patient tube within thehousing of the priming sensor, or (b) enclosed within the recessedsection of the housing of the priming sensor.

In accordance with a seventh aspect of the present disclosure, which maybe used in combination with any other aspect listed herein unless statedotherwise, the processor is configured to determine the first transitionbetween the no-tube state and the dry tube state by determining that achange in values of the measured first capacitance is greater than afirst transition threshold, and the processor is configured to determinethe second transition between the dry tube state and the wet tube stateby determining that a change in values of the measured secondcapacitance is greater than a second transition threshold.

In accordance with an eighth aspect of the present disclosure, which maybe used in combination with any other aspect listed herein unless statedotherwise, at least one of the first transition threshold and the secondtransition threshold corresponds to at least a doubling of therespective values of the measured capacitance from a first value to asecond value in less than 0.5 seconds, and wherein the second value isat least substantially constant for at least two seconds.

In accordance with a ninth aspect of the present disclosure, which maybe used in combination with any other aspect listed herein unless statedotherwise, the priming sensor includes fifth and sixth conductive plateslocated on opposing exterior sides of the housing, and third and fourthcapacitive sensors positioned and arranged to measure capacitances thatchange due to an external interference that is detected by at least oneof the fifth or sixth conductive plates positioned relative to the firstconductive plate, the third conductive plate, and the fourth conductiveplate.

In accordance with a tenth aspect of the present disclosure, which maybe used in combination with any other aspect listed herein unless statedotherwise, after detecting a change in the capacitance measured by thethird and fourth capacitive sensors, the processor is configured to, atleast one of refrain from detecting the states (i) to (iii), stop thepriming sequence, or output a message that is indicative of the detectedcapacitance interference.

In accordance with an eleventh aspect of the present disclosure, whichmay be used in combination with any other aspect listed herein unlessstated otherwise, the processor is further configured such that if thewet tube state is determined, a peritoneal dialysis treatment isenabled.

In accordance with a twelfth aspect of the present disclosure, which maybe used in combination with any other aspect listed herein unless statedotherwise, the peritoneal dialysis apparatus includes a user interfaceconfigured to display at least one of text or a graphic corresponding tothe determined state (i) to (iii).

In accordance with a thirteenth aspect of the present disclosure, whichmay be used in combination with any other aspect listed herein unlessstated otherwise, a sensor apparatus includes a housing including arecessed section configured to accept a portion of a tube. The housingincludes a first side including a first conductive plate, and a memberincluding a second conductive plate. The member is moveably connected toa second side of the recessed section for detecting insertion of theportion of the tube into the housing. The recessed section also includesa third side opposing the first side. The third side includes a thirdconductive plate disposed across from a top portion of the firstconductive plate, and a fourth conductive plate disposed across from abottom portion of the first conductive plate. The sensor apparatus alsoincludes a first capacitive sensor positioned and arranged to measure afirst capacitance between the first conductive plate and the thirdconductive plate, and a second capacitive sensor positioned and arrangedto measure a second capacitance between the third conductive plate andthe fourth conductive plate.

In accordance with a fourteenth aspect of the present disclosure, whichmay be used in combination with any other aspect listed herein unlessstated otherwise, the sensor apparatus is operable with a medical fluiddelivery machine including at least one pump and a control unit operablewith the first and second capacitive sensors to use the measured secondcapacitance to determine a first transition between (i) a no-tube stateand (ii) a dry tube state based on a distance of the second conductiveplate from the third and fourth conductive plates, and cause the atleast one pump to pump the fluid through the tube to conduct a primingsequence after the dry tube state is determined.

In accordance with a fifteenth aspect of the present disclosure, whichmay be used in combination with any other aspect listed herein unlessstated otherwise, the control unit is further configured to use themeasured first capacitance to determine a second transition between (ii)the dry tube state and (iii) a wet tube state based on a presence offluid within the tube, and transmit a message indicative that the tubeis primed after the wet tube state is determined.

In accordance with a sixteenth aspect of the present disclosure, whichmay be used in combination with any other aspect listed herein unlessstated otherwise, the control unit is further configured to increment acounter each time the wet tube state is determined, compare a value ofthe counter to a counter threshold, and determine the wet tube statewhen the value of the counter equals or exceeds the counter threshold.

In accordance with a seventeenth aspect of the present disclosure, whichmay be used in combination with any other aspect listed herein unlessstated otherwise, the control unit includes the first capacitive sensorand the second capacitive sensor.

In accordance with an eighteenth aspect of the present disclosure, whichmay be used in combination with any other aspect listed herein unlessstated otherwise, a medical fluid delivery apparatus includes a patienttube configured to receive dialysis fluid from a source of dialysisfluid, at least one pump configured to move dialysis fluid from thesource to the patient tube during a priming sequence, and a primingsensor including a housing having a recessed section configured toaccept a portion of the patient tube. The recessed section of thehousing includes a first side including a first conductive plate, and amember including a second conductive plate. The member is moveablyconnected to a second side of the recessed section and configured for adesired movement upon insertion of the portion of the patient tube intothe housing of the priming sensor. The recessed section also includes athird side opposing the first side. The third side includes a thirdconductive plate disposed across from a top portion of the firstconductive plate, and a fourth conductive plate disposed across from abottom portion of the first conductive plate. The medical fluid deliveryapparatus also includes a first capacitive sensor positioned andarranged to measure a first capacitance between the first conductiveplate and the third conductive plate, a second capacitive sensorpositioned and arranged to measure a second capacitance between thethird conductive plate and the fourth conductive plate, and a controlunit configured to operate with the pump, the first capacitive sensor,and the second capacitive sensor, the processor configured to performthe priming sequence.

In accordance with a nineteenth aspect of the present disclosure, whichmay be used in combination with any other aspect listed herein unlessstated otherwise, the control unit during the priming sequence uses themeasured second capacitance to determine a first transition between (i)a no-tube state and (ii) a dry tube state based on a distance of thesecond conductive plate from the third and fourth conductive plates.

In accordance with a twentieth aspect of the present disclosure, whichmay be used in combination with any other aspect listed herein unlessstated otherwise, the control unit during the priming sequence causesthe at least one pump to pump the fluid through the patient tube afterthe dry tube state is determined.

In accordance with a twenty-first aspect of the present disclosure,which may be used in combination with any other aspect listed hereinunless stated otherwise, the control unit during the priming sequenceuses use the measured first capacitance to determine a second transitionbetween (i) a dry tube state and (ii) a wet tube state based on apresence of fluid within the patient tube.

In accordance with a twenty-second aspect of the present disclosure,which may be used in combination with any other aspect listed hereinunless stated otherwise, the control unit during the priming sequencetransmits a message indicative that the patient tube is primed after thewet tube state is determined.

In a twenty-third aspect of the present disclosure, any of thestructure, functionality, and alternatives disclosed in connection withany one or more of FIGS. 1 to 26 may be combined with any otherstructure, functionality, and alternatives disclosed in connection withany other one or more of FIGS. 1 to 26 .

In light of the present disclosure and the above aspects, it istherefore an advantage of the present disclosure to provide an improvedpriming system, device, and method for a medical fluid delivery system,such as an automatic peritoneal dialysis (“APD”) system.

It is another advantage of the present disclosure to accurately detectwhen (i) a tube is present and (ii) a fluid reaches a certain positionwithin the tube regardless of ambient light, tube properties, and/orfluid properties.

It is yet another advantage of the present disclosure to provide apriming sensor and methodology that may be applied to different types ofmedical fluid delivery machines.

The advantages discussed herein may be found in one, or some, andperhaps not all of the embodiments disclosed herein. Additional featuresand advantages are described herein, and will be apparent from, thefollowing Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic view illustrating a diagram of an example medicalfluid delivery system including a priming sensor and a dialysis machine,according to an example embodiment of the present disclosure.

FIG. 2 is a perspective view illustrating a diagram of the primingsensor relative to the dialysis machine of the example medical fluiddelivery system of FIG. 1 , according to an example embodiment of thepresent disclosure.

FIG. 3 is a perspective view illustrating a diagram of a housing of thepriming sensor of FIGS. 1 and 2 , according to an example embodiment ofthe present disclosure.

FIG. 4 is a perspective view of the priming sensor of FIGS. 1 to 3before a tube is inserted therein, according to an example embodiment ofthe present disclosure.

FIG. 5 is a perspective view of the priming sensor of FIG. 4 after atube is inserted therein, according to an example embodiment of thepresent disclosure.

FIG. 6 is an elevation view of electrodes and/or conductive plates ofthe priming sensor of FIGS. 1 to 5 , according to an example embodimentof the present disclosure.

FIG. 7 is an elevation view of the priming sensor of FIGS. 1 to 5 ,according to another example embodiment of the present disclosure.

FIG. 8 is an elevation view of the priming sensor of FIGS. 1 to 5 ,according to a further example embodiment of the present disclosure.

FIG. 9 is an elevation view of the priming sensor of FIGS. 1 to 5 ,according to yet another example embodiment of the present disclosure.

FIG. 10 is a top view of a retaining clip and an electrode of thepriming sensor of FIG. 9 in a closed and resting position when a tube isnot inserted therein, according to an example embodiment of the presentdisclosure.

FIG. 11 is a top view of the retaining clip and the electrode of FIG. 10when a tube is inserted therein, according to an example embodiment ofthe present disclosure.

FIG. 12 is a schematic view of a circuit diagram showing the capacitorsformed by the electrodes of FIGS. 9 to 11 , according to an exampleembodiment of the present disclosure.

FIG. 13 is a schematic view of a diagram of a processor or control unitof the dialysis machine illustrated in FIG. 1 , according to an exampleembodiment of the present disclosure.

FIG. 14 is a graph of capacitance measured over a time period by thepriming sensor of FIGS. 9 to 13 , according to an example embodiment ofthe present disclosure.

FIG. 15 is a process flow diagram for determining a tube state of apatient tube, according to an example embodiment of the presentdisclosure.

FIG. 16 is a process flow diagram for determining a tube state of apatient tube, according to an example embodiment of the presentdisclosure.

FIGS. 17 to 23 are graphical screens that may be displayed by a dialysismachine to assist a patient in performing a priming procedure inpreparation of a dialysis therapy, according to example embodiments ofthe present disclosure.

FIGS. 24 to 26 are diagrams of the priming sensor of FIG. 1 , accordingto another example embodiment of the present disclosure.

DETAILED DESCRIPTION

A medical fluid delivery system is disclosed herein. The example medicalfluid delivery system may include an automated peritoneal dialysis(“APD”) machine, a hemodialysis machine, a medical fluid deliverymachine, or any other machine requiring one or more lines to be primed.The medical fluid delivery system includes a priming sensor configuredto detect when at least one tube or line set is present and when thetube is fully primed with an appropriate fluid, such as fresh dialysisfluid. The priming sensor includes one or more capacitive sensors.During a priming operation, the capacitive sensors perform capacitancemeasurements between two or more electrodes or conductive plates.Capacitance measurement values from the one or more capacitive sensorsmay be compared to one or more thresholds. The comparison is used todetermine different possible states of a patient tube including, forexample, a no-tube state, a dry tube state, and a wet tube state.

In some examples, the medical fluid delivery system is configured suchthat if a no-tube state is detected, the medical fluid delivery systemprovides an alert indicative that a patient tube needs to be insertedinto the priming sensor. The medical fluid delivery system may preventthe priming of the patient tube until the tube is detected by thepriming sensor. If a dry tube state is detected, the medical fluiddelivery system may begin and/or continue a priming sequence by pumpinga fluid from a fluid source into the patient tube. If a wet tube stateis detected, the medical fluid delivery system may stop the pumping ofthe priming fluid and/or end the priming sequence. In some embodiments,the medical fluid delivery system may be configured to confirm the wettube state by detecting the wet tube state multiple times (e.g., betweentwo and ten times in rapid succession to validate the wet tube state)before priming ends.

In some embodiments, the priming sensor disclosed herein includes ahousing having a recessed section configured to accept and/or hold apatient tube or line set. At least some of the electrodes and/orconductive plates are located on opposite sides of the recessed section.As such, the electrodes and/or conductive plates are located on oppositesides of a patient tube when the tube is inserted into the primingsensor. Placement of the tube in the priming sensor causes a capacitanceto change between the electrodes. In some embodiments, an electrodeand/or conductive plate may be placed on a retaining clip that islocated within the recessed section. Placement of the patient tubewithin the priming sensor causes the retaining clip to move toward atleast one stationary electrode or conductive plate located in therecessed section of the housing. The movement of the clip caused by theinsertion of the patient tube causes a change in capacitance, therebyproviding for detection of the patient tube in the priming sensor.

Additionally, at least some of the electrodes and/or conductive platesare located at different heights of the housing of the priming sensor.The electrodes and/or conductive plates are separated by at least onegap. The positioning of the electrodes and/or conductive plates atdifferent heights enables a fluid level to be determined based on acapacitance change when a dialysis fluid flows through the inserted tubeand past the electrodes and/or conductive plates. The capacitanceincreases when the dialysis fluid flows between the electrodes and/orconductive plates because an effective distance between the electrodesor plates is reduced when a fluid replaces air between the electrodes orplates.

The example system, method, and apparatus disclosed herein provide animprovement over known priming sensors that detect a tube state usinglight. Known light-based priming sensors activate all of the lightemitters individually. The emitters are activated to have the samebrightness level. The detected light from each emitter is compared to aseparate threshold (or combined into a ratio and compared to athreshold), where a tube state is determined based on a weighted averageof the threshold comparisons. Increases in ambient light decrease thesensor's ability to discern brightness levels corresponding to thedifferent tube states.

In contrast to known sensors, the example system, method, and apparatusdisclosed herein, uses capacitive sensing to detect tube state.Capacitive sensing is not affected by ambient light, environmentalcontamination, bubbles in a priming fluid, tube thickness, or tubeclarity/transparency. As a result, the capacitive sensing used by thepriming sensor disclosed herein is not prone to false state detectiondue to these common problems. Additionally, capacitance detection foreach of the states has a relatively high signal to noise ratio, e.g.,greater than 1000:1. The example capacitive sensors disclosed herein mayseal or otherwise enclose their electrodes, conductive plates, and otherelectronics within a sensor housing, thereby preventing fluid ingressand the issues that arise if the dialysis fluid contacts theelectronics. Capacitive sensors also have fewer parts with fewertolerance requirements compared to light-based sensors, and maytherefore be less expensive to manufacture.

In some embodiments, the priming sensor may be configured to detectelectrical interference from, for example, an operator. Generally, sincehumans affect electric fields, placement of an operator's hand near thepriming sensor may cause measured capacitance to change. Similarly,placement of a user device, such as a smartphone near the priming sensormay cause the electric field to change, thereby changing the capacitancemeasurement. In some embodiments, a processor or control unit for thepriming sensor is configured to detect significant variations incapacitance measurements. The processor or control unit may beconfigured to detect spikes and sharp drops in capacitance overrelatively short periods of time, such as less than one or two seconds,which are indicative of the presence of a hand or electronic device. Inresponse to such a detection, the processor or the control unit mayrefrain from concluding that a tube state change has occurred until theelectrical interference is removed. In some instances, the processor orthe control unit may also provide an error message on a display screenof the medical device indicating the detected interference and possiblyprovide an instruction to remove or eliminate the interference.

Additionally or alternatively, the priming sensor may be configured toprevent the external electrical interference. For instance, a housing ofthe priming sensor may include shielding, such as metallic plates,carbon filled conductive plastic, metal plated plastic, plastic sprayedwith conductive paint, etc. The shielding prevents electricalinterference from reaching the capacitive electrodes or conductiveplates. In other instances, the priming sensor may include an additionalcapacitive electrode or conductive plate that is positioned adjacent toan external side of the housing of the priming sensor. The additionalcapacitive electrode or conductive plate is configured to detect achange in electrical field external to the priming sensor. The processoror the control unit for the priming sensor may, for example, subtractthe detected change in capacitance due to the external source from thecapacitance change detected within the recessed section for determininga tube state.

The example disclosure refers to peritoneal dialysis and priming apatient tube. It should be appreciated that the example system,apparatus, and method disclosed herein can be provided to operate withany type of dialysis machine, including a hemodialysis machine or acontinuous replacement treatment machine. Moreover, the improved primingsensing discussed herein is not limited to dialysis, and may be usedwith any type of medical fluid machine, such as a medical deliverymachine (e.g., an infusion pump). Further, while the disclosure relatesto a patient tube, in other examples, other tubes may be primed using apriming sensor of the present disclosure, such as a heating tube, adrain tube, a medical fluid source tube, etc. Further, while thedisclosure references priming a tube using dialysis fluid, it should beappreciated that the example system, apparatus, and method may operatewith any type of medical fluid, including an intravenous drug, saline,renal therapy fluid, blood, sterile water, etc. Additionally, theimproved sensing may be used for any purpose in which it is desired toknow whether a tube is present or not and if so, whether the tubecontains a liquid.

Further, while the disclosure refers to capacitive sensors, it should beappreciated that other sensors could be used. For example, thecapacitive sensing disclosed herein could be replaced with inductivesensors. Moreover, the capacitive sensors may be replaced and/or used inconjunction with pressure sensors, radio-frequency (“RF”) sensors,proximity detection sensors, etc.

Dialysis System Embodiment

Referring now to the drawings, FIG. 1 illustrates an example medicalfluid delivery system 100, according to an example embodiment of thepresent disclosure. The medical fluid delivery system 100 in theillustrated embodiment includes a dialysis machine 102 configured toprovide renal failure therapy to one or more patients. Renal failuretherapy helps a patient balance water and minerals. Renal failuretherapy also helps excrete daily metabolic load by removing a patient'stoxic end products of nitrogen metabolism (urea, creatinine, uric acid,and others), which accumulate in blood and tissue. Renal failure therapyfor the replacement of kidney function is critical to many peoplebecause the treatment is life saving.

In some examples, the dialysis machine 102 is an APD machine. Theexample dialysis machine 102 is configured to deliver dialysis fluidinto a patient's peritoneal cavity via a catheter. The dialysis fluidcontacts the peritoneal membrane of the peritoneal cavity for a periodof time, which is referred to as a dwell period. Waste, toxins andexcess water pass from the patient's bloodstream, through the peritonealmembrane and into the dialysis fluid due to diffusion and osmosis, i.e.,an osmotic gradient occurs across the membrane. An osmotic agent indialysis provides the osmotic gradient. The used or spent dialysis fluidis drained from the patient, removing waste, toxins and excess waterfrom the patient. This cycle is repeated, e.g., multiple times.

There are various types of peritoneal dialysis therapies, includingcontinuous ambulatory peritoneal dialysis (“CAPD”), automated peritonealdialysis (“APD”), and tidal flow dialysis and continuous flow peritonealdialysis (“CFPD”). CAPD is a manual dialysis treatment. Here, thepatient manually connects an implanted catheter to a drain to allow usedor spent dialysis fluid to drain from the peritoneal cavity. The patientthen connects the catheter to a bag of fresh dialysis fluid to infusefresh dialysis fluid through the catheter and into the patient. Thepatient disconnects the catheter from the fresh dialysis fluid bag andallows the dialysis fluid to dwell within the peritoneal cavity, whereinthe transfer of waste, toxins and excess water takes place. After adwell period, the patient repeats the manual dialysis procedure, forexample, four times per day, each treatment lasting about an hour.Manual peritoneal dialysis requires a significant amount of time andeffort from the patient, leaving ample room for improvement.

Automated peritoneal dialysis (“APD”) is similar to CAPD in that thedialysis treatment includes drain, fill and dwell cycles. APD machines,such as the dialysis machine 102, however, perform the cyclesautomatically, typically while the patient sleeps. APD machines freepatients from having to perform the treatment cycles manually and fromhaving to transport supplies during the day. APD machines connectfluidly to an implanted catheter, to a source or bag of fresh dialysisfluid and to a fluid drain. APD machines pump fresh dialysis fluid froma dialysis fluid source, through the catheter and into the patient'speritoneal cavity. APD machines also allow for the dialysis fluid todwell within the cavity and for the transfer of waste, toxins and excesswater to take place. The source may include multiple sterile dialysisfluid bags.

APD machines pump used or spent dialysis fluid from the peritonealcavity, though the catheter, and to the drain. As with the manualprocess, several drain, fill and dwell cycles occur during dialysis. A“last fill” occurs at the end of APD and remains in the peritonealcavity of the patient until the next treatment.

In some embodiments, the dialysis machine 102 may be configured toperform hemodialysis (“HD”). During HD, the dialysis machine 102 isconfigured to use diffusion to remove waste products from a patient'sblood. A diffusive gradient occurs across the semi-permeable dialyzerbetween a patient's blood and an electrolyte solution called dialysateor dialysis fluid to cause diffusion. Hemofiltration (“HF”) is analternative renal replacement therapy that relies on a convectivetransport of toxins from the patient's blood. HF is accomplished byadding substitution or replacement fluid to the extracorporeal circuitduring treatment (typically ten to ninety liters of such fluid). Thesubstitution fluid and the fluid accumulated by the patient in betweentreatments is ultrafiltered over the course of the HF treatment,providing a convective transport mechanism that is particularlybeneficial in removing middle and large molecules (in hemodialysis thereis a small amount of waste removed along with the fluid gained betweendialysis sessions, however, the solute drag from the removal of thatultrafiltrate is not enough to provide convective clearance).

Hemodiafiltration (“HDF”) is a treatment modality that combinesconvective and diffusive clearances. HDF uses dialysis fluid flowingthrough a dialyzer, similar to standard hemodialysis, to providediffusive clearance. In addition, substitution solution is provideddirectly to the extracorporeal circuit, providing convective clearance.

The example dialysis machine 102 may be located in a center, a hospital,or a patient's home. A trend towards home dialysis exists today in partbecause home dialysis can be performed daily, offering therapeuticbenefits over in-center dialysis treatments, which occur typically bi-or tri-weekly. Studies have shown that frequent treatments remove moretoxins and waste products than a patient receiving less frequent butperhaps longer treatments. A patient receiving treatments morefrequently does not experience as much of a down cycle as does anin-center patient, who has built-up two or three days' worth of toxinsprior to treatment. In certain areas, the closest dialysis center can bemany miles from the patient's home causing door-to-door treatment timeto consume a large portion of the day. Home dialysis may take placeovernight or during the day while the patient relaxes, works or isotherwise productive. Much of the appeal of a home treatment for thepatient revolves around the lifestyle flexibility provided by allowingthe patient to perform treatment in his or her home largely according tohis or her own schedule.

Any of the above dialysis modalities performed by the dialysis machine102 may be run on a scheduled basis and may require a start-upprocedure. For example, dialysis patients typically perform treatment ona scheduled basis, such as every other day, daily, etc. Dialysistreatment machines typically require a certain amount of time beforetreatment for setup, for example, to run a priming and/or disinfectionprocedure. During a priming procedure, a fluid is pumped through one ormore dialysis tubes/lines and/or cassettes to remove air and/or in-lineparticulates. Priming dialysis tubes/lines and/or cassettes prevents airand/or the particulates from coming into contact with the patient.

The example dialysis machine 102 of FIG. 1 includes a priming sensor 104configured to detect appropriate priming of at least one dialysistube/line. In the illustrated embodiment, the priming sensor 104 isconfigured to detect priming of a patient tube 106. In otherembodiments, the priming sensor 104 is configured for priming ofadditional or alternative tubes, such as to-patient tubes/from-patienttubes of a continuous flow peritoneal dialysis set, drain tubes, heatingtubes, source fluid tubes, concentrate tubes, etc. For HD, the primingsensor 104 may be configured to prime an extracorporeal circuit, ato-dialyzer tube, a from-dialyzer tube, a source tube, a blood tube, asaline tube, and/or a drain tube. The patient tube 106 may be made ofany suitable medical grade material, such as polyvinyl chloride (“PVC”),silicone, or other non-PVC material. The tube 106 in one embodiment hasan inner or outer diameter that is equal to or less than 6 millimetersor 12 millimeters.

The dialysis machine 102 in the illustrated embodiment includes at leastone pump 110 configured to move dialysis fluid from a fluid source 112to the patient tube 106. The pump 110 may include any type of pump,including a peristaltic pump, a rotary pump, a gear pump, a platen, alinear actuator pump, a diaphragm pump, etc. The pump 110 is operated toprime the patient tube 106 with dialysis fluid. The pump 110 is alsooperated to provide dialysis fluid from the fluid source 112 to apatient when the patient tube 106 is connected to a catheter that isinserted into a patient's peritoneal cavity. Priming may alternativelyor additionally be performed using gravity where, for example, a sourceof fluid is provided at a head height above the dialysis machine 102.

In some embodiments, the dialysis machine 102 includes a disposablecassette, which is connected fluidly to the patient tube 106 and othertubing such as fill tubes and drain tubes. The cassette may include oneor more flexible membranes and associated chambers that operate withvalves and/or pumps in the dialysis machine 102. Priming the patienttube 106 may include priming the disposable cassette with the dialysisfluid in addition to the one or more connected tubes.

The fluid source 112 may include one or more containers of pre-mixeddialysis fluid. In some embodiments, the fluid source 112 may includecontainers or reservoirs of concentrate that have been mixed with purewater to form dialysis fluid. Additionally or alternatively, the fluidsource 112 may include an on-line source, such as a source of purifiedwater that is mixed with one or more concentrates to form dialysisfluid. Moreover, in some examples, the fluid source 112 may include afluid preparation device that provides prepared dialysis fluid to thedialysis machine 102 via one or more fluid connections.

The example dialysis machine 102 of FIG. 1 also includes one or moreprocessors 120 and one or more memories 122 that form a control unit115. The processor(s) 120 may include any type of device capable ofprocessing inputs and performing one or more calculations to determineone or more outputs. The processor(s) 120 may include a microcontroller,a microprocessor unit (“MPU”), a controller, an application specificintegrated circuit (“ASIC”), a central processing unit included on oneor more integrated circuits, etc. In some embodiments, the processor(s)120 may include a first processing device that is configured to processmeasured capacitances and determine a tube state and a second processingdevice that is configured to perform dialysis operations using, in part,data and instructions from the first processing device that areindicative of the tube state.

The memory 122 may include any volatile or non-volatile data/instructionstorage device. The memory 122 may include, for example, flash memory,random-access memory (“RAM”), read-only memory (“ROM”), ElectricallyErasable Programmable Read-Only Memory (“EEPROM”), etc. The examplememory 122 is configured to store one or more instructions executable bythe processor 120 to cause the processor 120 to perform operationsdisclosed herein. The instructions may be part of one or more softwareprograms or applications. References herein to the processor 120 beingconfigured to perform an operation may include embodiments in which thememory 122 stores instructions that are configured to cause theprocessor 120 to perform the described operation. The processor 120 andthe memory are collectively referred to as a control unit 115.

The example memory 122 is configured to store instructions that causethe processor(s) 120 to detect a tube state and/or operate the dialysismachine 102. The processor 120 (or a second processor of the dialysismachine 102) may also provide control signals or instructions to thepump 110 and/or cause the pump 110 to move dialysis fluid from the fluidsource 112 to the patient tube 106 during a priming sequence and duringa dialysis treatment. The operations performed by the processor(s) 120,when called upon to do so, also include periodically (e.g., every 1millisecond (“ms”), 10 ms, 250 ms, 100 ms, 500 ms, 1 second, 2 seconds,etc.) and/or continually measuring a capacitance between electrodesand/or conductive plates of the priming sensor 104. As disclosed herein,the memory 122 includes instructions that cause the processor 120 toanalyze values indicative of measured capacitance of the priming sensor104 to determine a state of the patient tube 106.

The example processor 120 is also configured to transmit one or moremessages to a user interface 124 of the dialysis machine 102 fordisplaying or otherwise conveying information on a display screen, suchas a touchscreen. The processor 120 may cause the user interface 124 todisplay instructions to a patient for preparing the dialysis machine 102for a treatment, including actions to prepare for a priming sequence.The user interface 124 may also display or otherwise convey indicationsthat are indicative of alert conditions, such as a warning to place thepatient tube 106 within the priming sensor 104 or to connect the patienttube 106 to a catheter after a priming sequence has been completed. Theuser interface 124 may include a touchscreen overlay and/orelectromechanical actuators, buttons, and/or switches to enable anoperator to input information. An input received by the user interface124 may include a prompt from an operator to begin a priming sequence ora dialysis treatment.

In some embodiments, the processor 120 and/or the memory 122 areincluded within the control unit 115. Further, the control unit 115 mayinclude one or more capacitive sensors 117 that operate with the primingsensor 104. In some examples, the sensors 117 are separate from theprocessor 120. In other examples, the sensors 117 may be included withinthe processor 120.

It should be appreciated that the dialysis machine 102 may includeadditional components for system preparation and/or performing dialysistreatments. The additional components may include pump actuators,compressors, pressure tanks, pneumatic equipment, valve actuators,heaters, online fluid generation equipment, fluid pressure sensors,fluid temperature sensors, conductivity sensors, and air detectionsensors. The dialysis machine 102 may additionally or alternativelyinclude blood leak detection sensors, filters, dialyzers, balancechambers, sorbent cartridges, etc. In addition, the dialysis machine 102may include one or more network connections (e.g., an Ethernetconnection) to enable the processor 120 to receive data/prescriptionsand transmit dialysis therapy status information to a remote orcentralized server via a network (e.g., the Internet). In an embodiment,the control unit 115 using the processor 120 may create a data structureor log that includes an indication of priming, detection of patient tubestate changes, a date/time when the state change occurred, and/orindications of alarms provided.

Priming Sensor Embodiments

FIG. 2 illustrates an embodiment of the priming sensor 104 positionedrelative to the dialysis machine 102 of the example medical fluiddelivery system 100 of FIG. 1 , according to an example embodiment ofthe present disclosure. In the illustrated example, the priming sensor104 is provided on or otherwise connected to a housing 201 of thedialysis machine 102 via a housing 202 of the priming sensor 104. Thehousing 202 is configured to retain the patient tube 106 in place toenable measurements to be made. The housing 202 may include or form aclip configured to engage the patient tube 106, which may include a cap204. For example, the housing 202 may include a cylindrical opening thatcorresponds to or aligns with corresponding structure of the tube 106 toretain the tube in place. A patient inserts, e.g., snap-fits the tube106 into the housing 202 by placing the patient tube 106 into an openchannel of the housing 202. The patient, in one embodiment, lowers thetube 106 until it is seated within the housing 202. While the housing202 is shown as being located on a side of the dialysis machine 102, inother embodiments, the housing 202 may be located on a top, front, back,and/or opposing surface of the dialysis machine.

The example cap 204 is configured to mechanically connect to an endconnector 206 of the patient tube 106. The cap 204 optionally includes ahydrophobic vent or filter that permits air to vent from the patienttube 106 during a priming sequence. The vent or filter, in anembodiment, helps prevents fluid from overflowing out of the patienttube 106. However, overfilling the tube 106 may cause the cap 204 toseparate from the tube. The priming sensor 104 is configured to detectwhen fluid reaches the end connector 206 (or just below the connector206) of the patient tube 106 to determine when fluid pumping or gravitypriming should stop. In such a case, the hydrophobic vent may not beneeded. After a priming sequence has been completed, a patient maydisconnect the cap 204 from the end connector 206. The patient may thenconnect the end connector 206 of the patient tube 106 to a catheter,which is fluidly connected to the patient's peritoneal cavity.

FIG. 2 also illustrates that the patient tube 106 may include a tubeclamp 208. The tube clamp 208 may be clamped to the tube 106 prior topriming to prevent fluid from unintentionally exiting the patient tube106. The tube clamp 208 is disengaged prior to the priming sequence butmay be clamped after priming while the patient connects the endconnector 206 to a catheter (or related transfer set) to begintreatment. The tube clamp 208 may optionally be omitted.

FIG. 3 illustrates the housing 202 of the priming sensor 104 of FIGS. 1and 2 , according to an example embodiment of the present disclosure.The example housing 202 of FIG. 3 includes a recessed section 302configured to accept and engage the tube 106. The recessed section 302may have a u-shape or semi-circular shape that at least partiallyencircles the tube 106. The recessed section 302 in the illustratedembodiment includes a lip 304 configured to receive and secure the tube106 in place. The recessed section 302 includes walls configured toenclose or otherwise encase one or more electrodes and/or conductiveplates, which are discussed in more detail in connection with FIGS. 6 to10 .

The example housing 202 also includes a retainer clip 306 (e.g., amember). The example retainer clip 306 includes a conductive plate orelectrode with an end that is connected to an interior section or therecessed section 302. The retainer clip 306 is configured to hold thetube 106 within the lip 304 of the housing 202 when the tube 106 isinserted. As such, the example retainer clip 306 is configured to causethe tube 106 to be properly aligned within the priming sensor 104. Theretainer clip 306 may be configured to provide a compressive force tofurther retain the tube 106 in place after insertion. As discussed inmore detail in connection with FIG. 9 , the movement of the retainerclip 306 towards the recessed section 302 when the tube 106 is insertedchanges a measured capacitance, which is used to detect between ano-tube state and a dry tube state.

The example housing 202 also includes exterior walls 308. The exteriorwalls 308 may include one or more shields to prevent or at least reduceelectrical field interference within the recessed section 302 due toexternal sources. Additionally or alternatively, the exterior walls 308may enclose or otherwise encase one or more electrodes and/or conductiveplates to sense changes to an electric field due to an external source,such as a smartphone or a hand of an operator.

FIGS. 4 and 5 illustrate the housing 202 of the priming sensor 104 ofFIG. 3 , according to example embodiments of the present disclosure.FIG. 4 shows the priming sensor 104 before a tube 106 is inserted. Asillustrated, the housing 202 includes a cutout area 402 configured toaccommodate or otherwise receive the retainer clip 306. As such, thecutout area 402 is dimensioned to correspond to dimensions of theretainer clip 306. A spring force or other compressive force of anelectrode or conductive plate holds the retainer clip 306 in a closedposition.

FIG. 5 illustrates the priming sensor 104 after the tube 106 isinserted. In the illustrated example, an operator inserts the tube 106into the priming sensor 104, which causes the retainer clip 306 to moveto an open position within the cutout area 402. The tube 106 is retainedwithin the recessed section 302 via the lip 304 and/or through acompressive force provided by the retainer clip 306. In the illustratedexample of FIG. 5 , the patient tube 106 includes the end connector 206and the cap 204. The recessed section 302 of the priming sensor 104 isconfigured to accept or otherwise secure the end connector 206 in place.

FIG. 6 illustrates electrodes and/or conductive plates of the primingsensor 104 of FIGS. 1 to 5 , according to an example embodiment of thepresent disclosure. In the illustrated example, a first electrode ormetallic sheet 602 is provided at a location that is adjacent to a firstportion of the tube 106 when the tube is inserted. In addition, a secondelectrode or metallic sheet 604 is provided at a location that isadjacent to a second portion of the tube 106 when the tube is inserted.The first and second electrodes 602 and 604 may be included or encasedwithin the housing 202 (not shown) of the priming sensor 104. Theelectrodes 602 and 604 are separated by a gap 605, which may have awidth that is between 0.5 millimeters (“mm”) and 2 centimeters (“cm)”.The electrodes 602 and 604 may have a width that is between 2 mm and 3cm. The electrodes 602 and 604 are connected to a capacitive sensor 606(e.g., a capacitance measuring device), which is configured to measure acapacitance between the electrodes 602 and 604. The electrodes 602 and604 (and other electrodes disclosed herein) may include conductiveplates, copper traces on a flexible PC board or cable, metallic plates,carbon filled conductive plastic, metal plated plastic, plastic sprayedwith conductive paint, etc. The capacitive sensor 606 (e.g., capacitivesensor 117 of FIG. 1 ) may be included within the processor 120 or thecontrol unit 115 of FIG. 1 or be provided separately. The capacitivesensor 606 may, for example, be provided on an electronics card orprinted circuit board provided with the control unit 115. The processor120, the capacitive sensor 606, and/or the control unit 115 is poweredvia a power source of the dialysis machine 102.

As shown in FIG. 6 , at a first time, a fluid level 610 in the tube 106is elevationally below the electrodes 602 and 604. As a result, thecapacitance measured at the sensor 606 is primarily based on thedielectric values of the air in the tube 106 and the tube itself. Later,the fluid level 610 rises in the tube 106 during a priming sequence toexpel the air. As such, the fluid 610 flows past the electrodes 602 and604. The presence of the fluid 610 in the portion of the tube 106 thatis adjacent to the electrodes 602 and 604 reduces an effective distancebetween the electrodes 602 and 604, thereby increasing a value of thecapacitance measured by the sensor 606. While the fluid 610 does notbridge the gap 605 by physically contacting the electrodes 602 and 604,the placement of the fluid 610 adjacent to the gap 605 is sufficient tochange the electric field around and between the electrodes 602 and 604.Detection of a change in electric field is indicative that the fluidlevel 610 has reached the end of the tube 106 at the electrodes 602 and604, which is indicative that the pump 110 can stop the primingprocedure. Further, the movement of a floating electrode closer to theelectrodes 602 and 604 also increases the measured capacitance, whichmay be used for detecting the presence of the tube 106.

FIG. 7 illustrates the priming sensor 104 of FIGS. 1 to 5 , according toanother example embodiment of the present disclosure. In the illustratedexample, the sensor 104 includes three electrodes and/or conductiveplates 602, 604, and 702, which are positioned at different elevationalheights with respect to the tube 106. The electrodes 602 and 604 areelectrically connected to a first capacitive sensor 606 a, while theelectrodes 604 and 702 are electrically connected to a second capacitivesensor 606 b. The capacitive sensors 606 a and 606 b may be includedwithin the processor 120 (and/or the control unit 115 andcommunicatively coupled to the processor 120) of FIG. 1 or be providedseparately.

The capacitive sensors 606 a and 606 b collectively provide anindication of fluid level. For example, detection of a fluid by thesecond sensor 606 b but not the first sensor 606 a is indicative thatthe fluid level has reached a height in the tube 106 greater than theend of the electrode 604 but less than a lower end of the electrode 602.Detection of the fluid level at such a level may cause the processor 120of the control unit 115 to decrease a pumping speed of the pump 110.Detection of the fluid by the first sensor 606 a is indicative that thefluid has reached at least a height in the tube 106 that is adjacent tothe electrode 602. Detection of the fluid level at this elevation maycause the processor 120 of the control unit 115 to stop the primingsequence using the pump 110. If neither of the sensors 606 a and 606 bdetects an increase in capacitance, the processor 120 of the controlunit 115 may be configured to cause the pump 110 to operate at normalpriming speed to prime the tube 106 with fluid.

FIG. 8 illustrates the priming sensor 104 of FIGS. 1 to 5 , according tofurther example embodiment of the present disclosure. In this example, afirst electrode or conductive plate 802 is placed on a first side of thetube 106, while a second electrode or conductive plate 804 is placed ona second side of the tube 106. As illustrated, the first electrode 802is placed on a first side of the recessed section 302 of the housing202, which is opposite to a second side of the recessed section 302,which contains the second electrode 804.

The electrodes 802 and 804 are electrically connected to a capacitivesensor 606, which is configured to measure a capacitance between theelectrodes. The measured capacitance includes values that are indicativeof the capacitance. As shown in FIG. 8 , when a fluid is not present,the capacitive sensor 606 measures a capacitance of the tube 106 and airwithin the tube. When the fluid displaces the air, the capacitive sensor606 measures a capacitance of the tube 106 and the fluid. Thecapacitance of the tube 106 itself is normalized or otherwise neglectedwhen detecting a change in capacitance due to the transition from air tofluid within the tube 106.

In some embodiments, a fluid level may be determined based on themeasured capacitance. For instance, the capacitance may be lower whenthe fluid level in the tube 106 is only aligned with a bottom portion orend of the electrodes 802 and 804 and greater when the fluid level isaligned with the top portion or end of the electrodes. The value of thecapacitive may be correlated via a table or other data structure to aheight in the tube 106. This value may be used by the processor 120 ofthe control unit 115 for gradually decreasing a speed of the pump 110 asthe fluid level approaches a top (open) end of the tube 106.

FIG. 9 illustrates the priming sensor 104 of FIGS. 1 to 5 , according toyet another example embodiment of the present disclosure. Similar to theexample of FIG. 8 , the electrodes 802 and 804 are positioned oppositeof one another. However, as shown in a plan view 900, the electrode 802is included within the retaining clip 306. As such, the electrode 802 ismoveable relative to the electrodes 804, 902 and 904, which are heldstationary via the housing 202. An end or base of the electrode 802 isconnected to a base or middle portion of the recessed section 302. Theretaining clip 306 is configured to pivot or bend at the end of theelectrode 802, thereby enabling the clip 306 to be moved between openedand closed positions. Further, the biased nature of the electrode 802 toreturn to its initial position within the recessed section 302 causesthe retaining clip 306 to provide a spring force on the tube 106 wheninserted into the priming sensor 104. It should be appreciated that insome examples, the electrode 802 is not electrically connected to otherportions of the priming sensor 104, thereby enabling it to floatelectrically.

The example priming sensor 104 of FIG. 9 also includes the electrodes902 and 904. As shown in plan view 900, the electrodes 902 and 904 areprovided on a side of the recessed section 302, which is opposite tothat of the electrode 804. The electrodes 902 and 904 are stationary andare configured to at least partially encircle the tube 106.

Similar to the example discussed in connection with FIG. 6 , theelectrodes 902 and 904 are positioned at different elevational heightsrelative to each other. In the illustrated example, the electrode 902 isplaced at a greater height or elevation than is the electrode 904,providing a gap therebetween. The electrodes 902 and 904 may have thesame width or different widths.

The electrodes 902 and 904 are electrically connected to a firstcapacitive sensor 606 a, which is configured to measure a capacitancevalue between the electrodes 902 and 904. In the illustrated example,the capacitive sensor 606 a is configured to detect a change between theno-tube state and the dry tube state. In the illustrated example, thecapacitive sensor 606 a is configured to detect a capacitance change asa result of the electrode 802 being moved closer to the electrodes 902and 904 when, for example, the tube 106 is inserted within the primingsensor 104. Movement of the electrode 802 towards the electrodes 902 and904 causes the measured capacitance to increase, which is indicativethat the tube 106 has been inserted within the priming sensor 106.

In some embodiments, the capacitive sensor 606 a may also be used todetect a capacitance change when a dialysis fluid level rises to bridgethe gap between the electrodes 902 and 904. As such, the capacitivesensor 606 a may be configured to additionally detect transitionsbetween a dry tube and a wet tube. Outputs from the sensor 606 a areused by the processor 120 of the control unit 115 to determine the drytube state and the wet tube state, as discussed in connection with FIG.6 .

As shown in FIG. 9 , the electrodes 804 and 902 are electricallyconnected to a second capacitive sensor 606 b. In the illustratedexample, the capacitive sensor 606 b is configured to detect acapacitance increase as a result of the fluid level rising between theelectrodes 804 and 902. The capacitive sensor 606 b is used to detecttransitions between a dry tube state and a wet tube state.

Similarly, electrodes 804 and 904 are electrically connected to a thirdcapacitive sensor 606 c. The third capacitive sensor 606 c is configuredto detect a capacitance increase as a result of fluid rising between theelectrodes 804 and 904. The capacitive sensor 606 c is used to detecttransitions between a dry tube state and a wet tube state.

In some embodiments, the outputs (or values indicative of measuredcapacitances) of the capacitive sensors 606 b and 606 c are addedtogether or otherwise combined by the processor 120 of the control unit115 for detecting the dry tube state and the wet tube state. In someembodiments, the processor 120 may compare the outputs from thecapacitive sensors 606 b and 606 c for determining a fluid level in thetube 106. For example, a significant difference between the measuredcapacitances is indicative that the fluid level in the tube 106 has notyet reached a height of the electrode 902 but has reached the height ofthe electrode 904. Detection of the fluid at this level may cause theprocessor 120 to reduce a pumping speed of the pump 110.

FIGS. 10 and 11 show a plan view of the priming sensor 104, according toan example embodiment of the present disclosure. FIG. 10 shows theretaining clip 306 and the electrode 802 in a closed and restingposition when the tube 106 is not inserted into the priming sensor 104.FIG. 10 also shows a base or end of the electrode 802 connected to amiddle-section or base of the recessed section 302. FIG. 11 shows theelectrode 802, including the retaining clip 306, bent, pivoted, orotherwise moved towards the electrode 902 as a result of the tube 106being inserted into the priming sensor 104. The retaining clip 306and/or the electrode 802 is configured such that the tube 106 can onlybe inserted into a desired alignment. The retaining clip 306 and/or theelectrode 802 may include, for example, a front end that is angled forreceiving and directing the tube 106 to a middle of the recessed section302. As discussed above in connection with FIG. 9 , placement of thetube 106 in the recessed section 302 causes the electrode 802 to movetowards electrodes 902 and 904, thereby increasing the measuredcapacitance.

FIG. 12 shows a circuit diagram 1200 for one embodiment of thecapacitors formed by the electrodes 802, 804, 902, and 904 of FIGS. 9 to11 , according to an example embodiment of the present disclosure. Asshown, the electrodes 804 and 902 form a first capacitor whileelectrodes 804 and 904 form a second, parallel capacitor. Thecapacitance of the first and second capacitors is based on a position ofthe electrode 802 relative to the electrodes 902 and 904. The electrodes902 and 904, as discussed herein, form a third capacitor.

Processor Embodiment

The example processor 120 of the control unit 115 of FIG. 1 isconfigured, in part, to determine a tube state based on capacitancemeasured by one or more capacitive sensors. FIG. 13 shows the processor120 of FIG. 1 , according to an example embodiment of the presentdisclosure. The processor 120 includes a first processing device 120 aand a second processing device 120 b. The first processing device 120 ais provided on a circuit board or processor board 1302. In the example,the first processing device 120 a is electrically connected to theelectrodes 902 and 904 via General Purpose Input Output (“GPIO”) tracesor lines. In some instances, current sources (or one or more powersources) may be connected to the GPIO lines to provide current to enablethe capacitance measurements. The current sources may provide, forexample, a current of 10 nA, 100 nA, 250 nA, 500 nA, 1000 nA, etc.

Also shown in FIG. 13 , the electrode 804 is electrically connected toground. The ground may be shared in common with a ground for theprocessing device 120 a, such that the processing device 120 a iselectrically connected to the electrode 804 via ground. In otherembodiments, the electrode 804 is instead connected to the processingdevice 120 a via a third GPIO line or trace. Further, as discussedabove, the electrode 802 is not electrically connected to the processingdevice 120 a and is therefore permitted to electrically float.

The processing device 120 a includes and/or operates with the capacitivesensors 606 a, 606 b, and 606 c, which measure capacitance via the GPIOlines. For example, the sensor 606 a operates with the processing device120 a to measure a capacitance between the electrodes 902 and 904 bydetermining a capacitance between the GPIO lines. The sensor 606 boperates with the processing device 120 a to measure a capacitancebetween the electrodes 804 and 902 by determining a capacitance betweenthe second GPIO line and ground. The sensor 606 c operates with theprocessing device 120 a to measure a capacitance between the electrodes804 and 904 by determining a capacitance between the first GPIO line andground.

FIG. 14 shows a graph 1400 illustrating example capacitance valuesmeasured by the sensors 606 a, 606 b, and 606 c of FIGS. 9 to 13 over atime period, according to an example embodiment of the presentdisclosure. The graph 1400 shows units of normalized capacitance over16.2 seconds. The capacitance may be normalized from measured valueshaving an order of magnitude of femtofarads (“fF”) or picofarads (“pF”).The graph 1400 shows a transition between a dry tube state and a wettube state, as measured by the capacitive sensors 606 b and 606 c. Asshown, the normalized capacitance changes by about 23000 units within afew tenths of a second as the liquid level in the tube 106 reaches theelectrodes 804, 902, and 904. The magnitude of the capacitance issubstantially level or consistent after the wet state is reached. Whenthe liquid level is reduced, the capacitance quickly falls off to returnto a normalized value of ‘0,’ thereby producing a square-shapedwaveform. As can be appreciated, the significant capacitance differencebetween the states provides a robust signal-to-noise ratio that isgreater than 1000:1, providing for accurate tube state detection. Itshould be appreciated that the graph 1400 is similar in magnitude andshape for transitions between the no-tube state and the dry tube state.

Returning to FIG. 13 , after measuring a capacitance, the firstprocessing device 120 a is configured to transmit one or more signals ormessages that are indicative of the capacitance to the second processingdevice 120 b. In the example, the second processing device 120 btransmits input instructions or signals via separate input lines. Thefirst processing device 120 a may use the input instructions or signalsfor sampling or performing capacitance measurements. For example, afirst input from the second processing device 120 b may instruct thefirst processing device 120 a to measure a capacitance of the firstcapacitive sensor 606 a, while the second input may instruct the firstprocessing device 120 a to measure a capacitance of the secondcapacitive sensor 606 b, while the third input may instruct the firstprocessing device 120 a to measure a capacitance of the third capacitivesensor 606 c.

In some embodiments, the first processing device 120 a is configured todetermine a tube state based on the measured capacitance valuesdetermined via the GPIO lines. The first processing device 120 atransmits an indication of each tube state or an indication of a tubestate change to the second processing device 120 b via, for example, apulse-width modulated (“PWM”) signal or an analog signal produced by adigital-to-analog converter (“DAC”) within the first processing device120 a. In alternative examples, the PWM signal may be replaced by adigital signal or instruction that is indicative of the tube state.

In some embodiments, the first processing device 120 a is configured tosample or perform multiple capacitance measurements before conclusivelydetermining that a tube state has changed. For example, if a thresholdnumber of measurements (e.g., one, two, three, five, ten, etc.) areindicative of the same tube state within a threshold time period (e.g.,10 ms, 100 ms, 250 ms, 500, ms, 1 second, 2 seconds, 5 seconds, etc.),the first processing device 120 a determines the tube state has in factchanged. If at least one of the thresholds is not met, the processingdevice 120 a refrains from determining a tube state change. Theabove-situation may occur when electrical interference is present due toan operator's hand or electronic device.

Alternatively, the first processing device 120 a transmits an indicationof the measured capacitances to the second processing device 120 b via aPWM signal or an analog signal produced by the DAC within the firstprocessing device 120 a. A pulse width may correspond to a value of themeasured capacitance. In alternative examples, the PWM signal may bereplaced by a digital signal or instruction that is indicative ofmeasured capacitance. After receiving capacitance values from the firstprocessing device 120 a, the second processing device 120 b isconfigured to determine a tube state. In some examples, the processingdevice 120 b may sample or perform multiple capacitance measurements (bytransmitting messages via the separate input lines to the firstprocessing device 120 a) for determining tube state. If a thresholdnumber of measurements (e.g., one, two, three, five, ten, etc.) areindicative of the same tube state within a threshold time period (e.g.,10 ms, 100 ms, 250 ms, 500, ms, 1 second, 2 seconds, 5 seconds, etc.),the second processing device 120 b determines the tube state has in factchanged. If at least one of the thresholds is not met, the processingdevice 120 b refrains from determining a tube state change.

FIG. 15 illustrates an example procedure 1500 for determining a tubestate of the patient tube 106 of FIG. 1 , according to an exampleembodiment of the present disclosure. The example processor 120 of thecontrol unit 115 is configured to execute or operate the procedure 1500shown in FIG. 15 . To begin, the example processor 120 receives anindication or determines that a patient is to start a dialysis treatment(block 1502). The example processor 120 may receive an input via theuser interface 124 that a patient has selected to begin a treatment.Alternatively, the processor 120 may determine via an electronicallystored schedule that a patient is to undergo a dialysis treatment. Toprepare for the treatment, the example processor 120 operates a setuproutine in one embodiment, which may include connecting tubes toappropriate containers and performing a priming procedure. When it istime to prime the patient tube 106, the example processor 120 transmitsa message 1501 for display via the user interface 124 that the patientis to inset the patient tube 106 into the priming sensor 104 (block1504). FIG. 17 illustrates an example screen layout 1700 that may bedisplayed by the user interface 124 based on the message 1501. Thescreen layout 1700 includes text and an illustration regarding how thepatient tube 106 is to be placed within the priming sensor 104.

To determine if the patient correctly inserted the tube 106 into thepriming sensor 104, the example processor 120 is configured to performone or more capacitive measurements to determine a tube state (block1506). For each capacitive measurement performed, the processor 120receives sampled output data 1503 from one or more of the capacitivesensors 606, which is processed to determine a tube state, as discussedabove in connection with FIGS. 9 to 14 . If the no-tube state isdetected, the processor 120 is configured to transmit one or moremessages 1507 indicative that the patient tube 106 is missing. FIG. 18illustrates a diagram of a screen layout 1800 that may be displayed bythe user interface 124 based on the message 1507. The screen layout 1800includes a pop-up window alerting the patient that the patient tube 106has not been inserted.

Returning to FIG. 15 , if a dry tube state is detected, the exampleprocessor 120 transmits one or more messages 1509 indicative that thepatient is to connect a tube to a fluid source (block 1508). In otherembodiments, the message 1509 may instruct a patient to begin a primingsequence. FIG. 19 shows a diagram of a screen layout 1900 that may bedisplayed by the user interface 124 based on the message 1509. Thescreen layout 1900 includes text and images regarding how a fluid sourceis to be connected to one or more source tubes of a dialysis machine.After the patient has connected the tubes, the patient may select thepriming button shown in the screen layout 1900. Selection of the primingbutton provides an indication for the processor 120 to begin a primingsequence (block 1510). The priming sequence includes causing at leastone pump 110 to move dialysis fluid from at least one source container112 to the patient tube 106. During this sequence, the processor 120receives sampled output data 1503 from performing multiple capacitancemeasurements or sampling of capacitance measurements that are conductedby the capacitive sensors 606 (block 1512). In addition, during thissequence, the processor 120 may cause a screen layout 2000 shown in FIG.20 to be displayed on the user interface 124, which is indicative that apriming sequence is being run.

For each detection of a dry tube state, the processor 120 may incrementa threshold counter and determine whether the counter exceeds athreshold (block 1514). If the threshold is not exceeded within aspecified time period (e.g., 250 ms, 500 ms, 1 second, 3 seconds, 10seconds, 20 seconds, 40 seconds, etc.), the patient tube 106 is not ableto prime within an expected time period and may have an occlusion, leak,constriction, or other condition that is preventing dialysis fluid fromfilling the tube. In an attempt to correct the situation, the processor120 is configured to transmit one or more messages 1515, which causesscreen layout 2100 of FIG. 21 to be displayed. In addition, an alarm maybe activated. The screen layout 2100 includes text indicative of thepriming error and instructions for the patient to check the tubes fromthe source fluid and the patient tube 106. After a patient hasidentified and corrected the issue with the tubes, the patient mayselect the next button to re-start the priming sequence.

Returning to block 1512, if a wet tube state is detected within athreshold time, the example processor 120 may be configured to stop thepump 110 from priming (block 1516). In some embodiments, the exampleprocessor 120 is configured to confirm that the prime has been correctlyperformed. The example processor 120 may also transmit one or moremessages 1517 with information instructing the patient to connect thepatient tube 106 to a patient line set and/or catheter to begintreatment (block 1518). FIG. 22 illustrates a diagram of a screen layout2200 that may be displayed by the user interface 124 based on themessage 1517. The screen layout 2200 includes text and an imageproviding a patient information regarding how to connect the patienttube 106 to a line set or catheter.

Returning to FIG. 15 , the example processor 120 is configured to usethe priming sensor 104 to determine if the patient tube 106 is stillpresent in the sensor (block 1520). The processor 120 receives one ormore sets of sampled output data 1503 to determine if the tube is stillin the priming sensor 104. If the tube is still present, the processor120 transmits one or more messages 1521 indicative that the patient isto remove the tube from the priming sensor 104. FIG. 23 illustrates adiagram of a screen layout 2300 that may be displayed by the userinterface 124 based on the message 1521. The screen layout 2300 includesa pop-up window providing a warning that that the patient tube has notbeen removed from the priming sensor for connection to a line set orcatheter. If the patient tube 106 is no longer detected, the exampleprocessor 120 is configured to end the priming sequence and/or enablethe dialysis therapy to begin.

FIG. 16 shows a diagram of an example procedure 1600 configured todetermine a tube state of the patient tube 106 for a priming sequence,according to an example embodiment of the present disclosure. Theexample procedure 1600 may be executed or performed by the processor 120of FIG. 1 . Further, the processor 1600 may operate according to one ormore instructions stored in the memory 122, which when executed by theprocessor 120, cause the processor 120 to perform the describedoperations. In some embodiments, the processor 120 may additionallynormalize the measured capacitance values.

The example procedure 1600 begins when the processor 120 performs apriming sequence and provides power to the priming sensor 104 (block1602). The example processor 120 calibrates the capacitive sensor 606 aof FIG. 9 (block 1604). The processor 120 may calibrate the sensor 606 aby determining steady state measured capacitance. The processor 120 maydetermine an average of the measured capacitance values for calculatinga baseline value 1605. After calibration, the processor 120 stores thedetermined baseline capacitance value 1605 to the memory 122.

The processor 120 then computes a sense threshold T (block 1606). Thethreshold T is a capacitance value that is greater than the baselinevalue 1605. In some embodiments, the processor 120 determines thethreshold T as being 2×, 3×, 4×, 5×, 7×, 10×, 15×, 20×, etc., greaterthan the baseline value 1605. In other embodiments, the processor 120determines the threshold T as being a specified number of fF or pF abovethe baseline value. Measured capacitance values below the threshold Tare determined by the processor 120 to correspond to a no-tube state,while measured capacitance values above the threshold T are determinedby the processor 120 to correspond to a dry tube state. For instance,the processor 120 compares measured capacitance values from the sensor606 a to the threshold T (block 1608). If the measured capacitancevalues are less than the threshold T, the processor 120 determines themeasured values correspond to the no-tube state (block 1610). In someinstances, the processor 120 may also update a counter, where nodetections of a no-tube state within a specified time period may causethe processor 120 to output an error message or activate an alert. Theprocessor 120 then continues to compare (or sample) subsequent measuredcapacitance values from the capacitive sensor 606 a to the threshold T.

Returning to block 1608, if the measured capacitance values are greaterthan or equal to threshold T, the processor 120 determines the measuredvalue corresponds to a dry tube state (block 1612). In some instances,the processor 120 may only determine a dry tube state if a thresholdnumber of dry state tube detections are made within a specified timeperiod (e.g., two, five, or ten detections within 100 ms, 250 ms, 500ms, 1 s, 2 s, 5 s, etc.).

The processor 120 next calibrates the capacitive sensor 606 b and/or 606c of FIG. 9 (block 1614). In some embodiments, the processor 120calibrates the capacitive sensors 606 a, 606 b, and 606 c atsubstantially the same time or at the same time within the exampleprocedure 1600. The processor 120 may calibrate the sensor 606 b and/or606 c by determining steady state measured capacitances. The processor120 may determine an average of the measured capacitance values forcalculating a baseline value 1615. After calibration, the processor 120stores the determined baseline capacitance value 1615 to the memory 122.

The processor 120 of the control unit 115 then computes a sensethreshold W (block 1616). The threshold W is a capacitance value that isgreater than the baseline value 1615. In some embodiments, the processor120 determines the threshold Was being 2×, 3×, 4×, 5×, 7×, 10×, 15×,20×, etc., greater than the baseline value 1615. In other embodiments,the processor 120 determines the threshold W as being a specified numberof fF or pF above the baseline value. Measured capacitance values belowthe threshold W are determined by the processor 120 to correspond to adry tube state, while measured capacitance values above the threshold Ware determined by the processor 120 to correspond to a wet tube state.

After the threshold W is determined, the processor 120 is ready todetermine a tube state. As shown in FIG. 16 , the processor 120 isconfigured to compare measured capacitance values from the sensor 606 ato the threshold T (block 1618). If the measured capacitance values areless than the threshold T, the processor 120 determines the measuredvalues correspond to the no-tube state (block 1620). The processor 120continues this loop until the measured capacitance values are greaterthan or equal to the threshold T The processor 120 then comparesmeasured capacitance values from the sensor 606 b and/or 606 c to thethreshold W (block 1622). In some instances, the processor 120 maycombine the measured capacitance values from the sensors 606 b and 606 cfor the baseline value 1615, the threshold W, and state detection. Ifthe measured capacitance values are less than the threshold W, theprocessor 120 determines the measured values correspond to the dry tubestate (block 1624). The processor 120 may return to block 1618 anddetermine if the tube is still present in the priming sensor 104 ordetermine if the tube has been removed. In some instances, the processor120 may also update a counter, where zero detections of a wet tube statewithin a specified time period may cause the processor 120 to output anerror message or activate an alert indicative of an occlusion, tubeleak, etc. The processor 120 then continues to compare (or sample)subsequent measured capacitance values from the capacitive sensors 606 band/or 606 c to the threshold W.

Returning to block 1622, if the measured capacitance values are greaterthan or equal to threshold W, the processor 120 determines the measuredvalue corresponds to a wet tube state (block 1626). In some instances,the processor 120 of the control unit 115 may only determine a wet tubestate if a threshold number of wet state tube detections are made withina specified time period (e.g., two, five, or ten detections within 100ms, 250 ms, 500 ms, 1 s, 2 s, 5 s, etc.). After detecting a wet tubestate, the example processor 120 may end a priming sequence, therebyending the example procedure 1600. Alternatively, the processor 120returns to block 1618 and determines if the tube has been removed fromthe priming sensor 104.

Addition Priming Sensor Embodiment

FIG. 24 shows a diagram of the priming sensor 104 of FIG. 1 , accordingto another example embodiment of the present disclosure. In theillustrated example, the priming sensor 104 includes a housing 2402 thatis provided in a u-shape. The housing 2402 includes a first arm or side2404 and a second arm or side 2406. The housing 2402 also includes ajoint or hinge 2408 that enables the second arm or side 2406 to rotateor pivot with respect to the first arm or side 2404 or a base 2405 ofthe u-shaped housing 2402 (e.g., a third side).

In the illustrated example, the first arm or side 2404 includesconductive plates 2410 and 2412. The plates may be solid and placedadjacent to the other. Alternatively, the plates may be interleaved in acomb or finger configuration to provide a relatively broad sensitivearea. The conductive plate 2410 is provided at a first height relativeto the patient tube 106 and the conductive plate 2412 is provided at asecond height, below the conductive plate 2410. In some examples, theplates 2410 and 2412 have the same lengths, widths, and/or heights.Further, the plates 2410 may be separated by a few millimeters up to afew centimeters. A capacitive sensor 2414 is configured to measure acapacitance between the plates 2410 and 2412. The processor 120 isconfigured to use the capacitance values measured by the sensor 2414 todiscriminate between the wet tube state and the dry tube state bydetermining when capacitance values change as a result of cleansingfluid in the tube 106 bridging the gap between the plates 2410 and 2412.

FIG. 24 also shows that the second side or arm 2406 of the housing 2402includes conductive plate 2416 while the base side 2405 of the housingincludes conductive plates 2418 and 2420. The conductive plates 2418 and2420 are electrically connected to a capacitive sensor 2422, which isconfigured to measure capacitance between the plates 2418 and 2420. Theconductive plate 2416 is configured to electrically float. Theconductive plates 2418 and 2422 and sensor 2422 are configured to detect(via the processor 120) when the conductive plate 2416 is moved closerto the plates 2418 and 2422 by measuring an increase in capacitance.

FIGS. 25 and 26 show diagrams illustrating how the joint or hinge 2408enables the second arm or side 2406 to rotate or pivot with respect tothe third arm or side 2405. The example hinge 2408 may be molded as partof the housing 2402 as a living hinge. In other examples, the hinge 2408may include a barrel hinge, a pivot hinge, a case hinge, or combinationsthereof. In some instances, the hinge 2408 may be part of a member(e.g., the second arm 2406) that is configured for a desired movementupon insertion of a tube 106 into the housing 2402 of the priming sensor104. In this embodiment, the conductive plates 2418 and 2420 may beprovided on the third side 2405 of the housing 2402 that forms a base ofthe u-shape, whereby the hinge 2408 connects the second side 2406 to thethird side 2405.

FIG. 25 shows the second side 2406 rotated, via the hinge 2408, to beparallel with the first side 2404 of the housing 2402 when the tube 106is inserted therein. In this configuration, the conductive plate 2416 ismoved closer towards the conductive plates 2418 and 2420, which causesthe capacitance measured by the sensor 2422 to increase. In theillustrated example, the sensor 2422 measures the capacitance betweenthe conductive plates 2418 and 2420. Moving the conductive plate 2416closer towards the plates 2418 and 2420 causes the capacitance between(and around) the plates 2418 and 2420 to increase. Accordingly, theprocessor 120 uses output from the sensor 2422 to discriminate between adry tube state and a no-tube state.

FIG. 26 shows an example when the tube 106 is removed from the housing2402. In this example, the second side 2406 is rotated or pivoted at thehinge 2408 to be angled toward or be closer to the first side 2404. Inthis configuration, the conductive plate 2416 is moved away from theconductive plates 2418 and 2420, which causes the capacitance measuredby the sensor 2422 to decrease. The movement of the second side 2406increases an area of a gap 2600 between the conductive plates 2416,2418, and 2420. In some embodiments, the gap 2600 may include air or acompressible foam that fills the gap between the second side 2406 andthe third side 2405 of the housing 2402.

CONCLUSION

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. A peritoneal dialysis apparatuscomprising: at least one pump configured to move dialysis fluid from asource to a patient tube during a priming sequence; a housing having arecessed section configured to accept a portion of the patient tube, thehousing including a first electrode located adjacent to the portion ofthe patient tube when the portion of the patient tube is inserted intothe housing, and a second electrode located above the first electrodeand separated from the first electrode by a gap, a capacitive sensorpositioned and arranged to measure a capacitance between the firstelectrode and the second electrode; and a processor configured tooperate with the at least one pump and the capacitive sensor, theprocessor configured to use the measured capacitance to determine atransition between a dry tube state and a wet tube state when thedialysis fluid rises within the portion of the patient tube to a levelof at least the second electrode, and cause the at least one pump tostop pumping the dialysis fluid through the patient tube for the primingsequence after the wet tube state is determined.
 2. The apparatus ofclaim 1, further comprising a user interface communicatively coupled tothe processor, wherein the processor is further configured to cause theuser interface to display information indicative that the patient tubeis primed after the wet tube state is determined.
 3. The apparatus ofclaim 1, wherein the processor is further configured to: use themeasured capacitance to determine a transition between a no-tube stateand the dry tube state when the portion of the patient tube is insertedinto the housing; and cause the at least one pump to pump the dialysisfluid through the patient tube for the priming sequence after the drytube state is determined.
 4. The apparatus of claim 3, furthercomprising a user interface communicatively coupled to the processor,wherein the processor is further configured to cause the user interfaceto display information indicative that the priming sequence can beginafter the dry tube state is determined.
 5. The apparatus of claim 3,wherein the processor is configured to determine the transition betweenthe no-tube state and the dry tube state by determining that a change invalues of the measured capacitance is greater than a first transitionthreshold, and wherein the processor is configured to determine thetransition between the dry tube state and the wet tube state bydetermining that a change in values of the measured capacitance isgreater than a second transition threshold.
 6. The apparatus of claim 5,wherein at least one of the first transition threshold or the secondtransition threshold corresponds to at least a doubling of therespective values of the measured capacitance from a first value to asecond value in less than 0.5 seconds, and wherein the second value isat least substantially constant for at least two seconds.
 7. Theapparatus of claim 1, wherein the processor is further configured to:use the measured capacitance to determine no transition between theno-tube state and the dry tube state; and cause the user interface todisplay an alert to insert the patient tube into the housing.
 8. Theapparatus of claim 1, wherein the gap is between 0.5 millimeters and 2centimeters.
 9. The apparatus of claim 1, wherein the first electrodeand the second electrode each have a width that is between 2.0millimeters and 3.0 centimeters.
 10. The apparatus of claim 1, whereinthe first electrode and the second electrode each includes a conductiveplate, a copper trace, a metallic plate, carbon filled conductiveplastic, metal plated plastic, or plastic sprayed with conductive paint.11. The apparatus of claim 1, wherein the processor is furtherconfigured such that when the wet tube state is determined, a peritonealdialysis treatment is enabled.
 12. The apparatus of claim 1, wherein theprocessor is further configured to: increment a counter each time thewet tube state is determined; compare a value of the counter to acounter threshold; and determine the wet tube state when the value ofthe counter equals or exceeds the counter threshold.
 13. The apparatusof claim 1, wherein the processor is further configured to: use themeasured capacitance to determine no transition between the dry tubestate and the wet tube state; and cause a user interface to display analert indicative of a possible leak or patient line occlusion.
 14. Aperitoneal dialysis apparatus comprising: at least one pump configuredto move dialysis fluid from a source to a patient tube during a primingsequence; a housing having a recessed section configured to accept aportion of the patient tube, the housing including a first electrodelocated adjacent to the portion of the patient tube when the portion ofthe patient tube is inserted into the housing, a second electrodelocated above the first electrode and separated from the first electrodeby a gap, a capacitive sensor positioned and arranged to measure acapacitance between the first electrode and the second electrode; and aprocessor configured to operate with the at least one pump and thecapacitive sensor, the processor configured to use the measuredcapacitance to determine a transition between a no-tube state and a drytube state when the portion of the patient tube is inserted into thehousing, and cause the at least one pump to pump the dialysis fluidthrough the patient tube for the priming sequence after the dry tubestate is determined.
 15. The apparatus of claim 14, further comprising auser interface communicatively coupled to the processor, wherein theprocessor is further configured to cause the user interface to displayinformation indicative that the priming sequence can begin after the drytube state is determined.
 16. The apparatus of claim 14, wherein theprocessor is further configured to: use the measured capacitance todetermine no transition between the no-tube state and the dry tubestate; and cause the user interface to display an alert to insert thepatient tube into the housing.
 17. The apparatus of claim 14, whereinthe processor is further configured to: increment a counter each timethe dry tube state is determined; compare a value of the counter to acounter threshold; and determine the dry tube state when the value ofthe counter equals or exceeds the counter threshold.
 18. The apparatusof claim 14, wherein the processor is configured to determine thetransition between the no-tube state and the dry tube state bydetermining that a change in values of the measured capacitance isgreater than a transition threshold.
 19. The apparatus of claim 14,wherein the gap is between 0.5 millimeters and 2 centimeters, andwherein the first electrode and the second electrode each have a widththat is between 2.0 millimeters and 3.0 centimeters.
 20. The apparatusof claim 14, wherein the first electrode and the second electrode eachincludes a conductive plate, a copper trace, a metallic plate, carbonfilled conductive plastic, metal plated plastic, or plastic sprayed withconductive paint.